A selective review of the first 20 years of instrumental variables models in health-services research and medicine

被引：15
作者：
Cawley, John [1 ,2 ]
机构：
[1] Cornell Univ, Dept Policy Anal & Management, Ithaca, NY 14853 USA
[2] Univ Sydney, Sch Econ, Sydney, NSW 2006, Australia
来源：
JOURNAL OF MEDICAL ECONOMICS | 2015年 / 18卷 / 09期
关键词：
Instrumental variables; Econometrics; Methods; Health;
D O I：
10.3111/13696998.2015.1043917
中图分类号：
F [经济];
学科分类号：
02 ;
摘要：
Background: The method of instrumental variables (IV) is useful for estimating causal effects. Intuitively, it exploits exogenous variation in the treatment, sometimes called natural experiments or instruments. This study reviews the literature in health-services research and medical research that applies the method of instrumental variables, documents trends in its use, and offers examples of various types of instruments. Methods: A literature search of the PubMed and EconLit research databases for English-language journal articles published after 1990 yielded a total of 522 original research articles. Citations counts for each article were derived from the Web of Science. A selective review was conducted, with articles prioritized based on number of citations, validity and power of the instrument, and type of instrument. Results: The average annual number of papers in health services research and medical research that apply the method of instrumental variables rose from 1.2 in 1991-1995 to 41.8 in 2006-2010. Commonly-used instruments (natural experiments) in health and medicine are relative distance to a medical care provider offering the treatment and the medical care provider's historic tendency to administer the treatment. Less common but still noteworthy instruments include randomization of treatment for reasons other than research, randomized encouragement to undertake the treatment, day of week of admission as an instrument for waiting time for surgery, and genes as an instrument for whether the respondent has a heritable condition. Conclusion: The use of the method of IV has increased dramatically in the past 20 years, and a wide range of instruments have been used. Applications of the method of IV have in several cases upended conventional wisdom that was based on correlations and led to important insights about health and healthcare. Future research should pursue new applications of existing instruments and search for new instruments that are powerful and valid.
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页码：721 / 734
页数：14
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